He says:It is appropriate to conclude with two photographs of the exhibited makeshift fender, because they are in themselves a mystery. In the first photograph below AS17-137-20979, the details of the four spare laminated maps used to assemble the fender can be seen on the outside of the curved surface. However, in the second photograph the details of the map are on the inside of the curved surface. Perhaps the curators at the Smithsonian made a mistake and curved the maps the wrong way. It seems odd that no one took the trouble to correctly display such an important item that had been brought back from the Moon.

But as far as I can see (and apologies if this has already been addressed, I did search but didn't find anything about this specific point) there is no printing on the outside curved surface of the maps in situ on the rover. At first glance it looks as though there is, but if you look at a high-res copy of the photograph, it appears to be an illusion caused by patches of dust (and helped by the presence of a reseau cross on top of the map).

Comparing the pattern of the duct tape, you can clearly see that it is the same fender, albeit photographed from the opposite angle to the moon picture. Note the small overlap of tape sticking out near the middle, and the thin strip of tape over one end but not the other:

The National Air and Space Museum actually has four images of the fender, not just the one low-res picture Willis uses. One image clearly shows that the actual printed side of the maps has an obvious black grid-square pattern, which is notably absent from what he claims is the printed side in the moon photo:

It also shows a view that more closely matches the moon image, with the fender in the same orientation:

It's plain to see that the pattern of duct tape is identical. There is additional damage that was not present in the moon photo, however some of the damaged sections and marks can also be matched up: